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Spodumene

Description: Lithium sourcing feldspar

Oxide Analysis Formula
Li2O 8.01% 1.00
Al2O3 27.41% 1.00
SiO2 64.59% 4.00
Oxide Weight 372.07
Formula Weight 372.07

Notes

The name is from the Greek spodos, meaning burnt to ash. Spodumene is a silicate mineral often referred to as lithium feldspar. Its mineral form is characterized by hard needle-like grains of brilliant white color. It is used in ceramics as a source of lithia.

In ceramics, lithia is a very powerful flux, especially when used in conjunction with potash and soda feldspars. As one of only a few natural lithium source materials, spodumene is a valuable component in glass and ceramic/enamel glazes (Li2O reduces thermal expansion, melting temperature and viscosity of the glaze melt).

Spodumene is only slightly soluble (in contrast to lithium carbonate). Because spodumene is a natural combination of silica, alumina and lithia it melts better than a chemically equivalent mixture of lithium carbonate, kaolin and silica. Since almost all raw glazes contain kaolin and silica it is normally fairly easy to juggle recipe ingredients, using glaze chemistry, to replace lithium carbonate with spodumene (provided, of course, that the lithium carbonate percentage is not too high). Spodumene can also be substituted for part of the feldspar complement in a recipe without disturbing overall chemistry too much (other than substituting Li2O for KNaO).

That being said, the price of spodumene is increasing rapidly as industry learns to extract the lithium from it. This is being done via calcination to convert the crystal structure from monoclinic alpha (a-form) to tetragonal beta (β-form). Calcination is then further employed in the acid roasting of spodumene, so that lithium can be extracted as water-soluble lithium sulfate.

Some types of spodumene do contribute to the formation of bubbles in the glaze slurry. You can wash spodumene before use to alleviate this issue (mix it well in plenty of hot water, allow to settle overnight, pour off the water the next day and dry it).

Spodumene is a little more readily fusible than petalite since it is higher in lithium. It is considered a better source of Li2O for frits. Some sources quote the percentage of Li2O in molar percent rather than weight percent (resulting in a much higher figure).

Spodumene powder, although heavy, dusts easily and is very unpleasant to smell or breathe. And it sticks to tools, scoops and containers. Good ventilation equipment is needed to be able to mix glazes using it.

Related Information

Spodumene ore

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Spodumene ore: Typically refiners want 6% or more LiO2 content.

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Sourcing Li2O from spodumene instead of lithium carbonate comes at a cost

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Two very melt fluid glazes

Lithium carbonate is now ultra-expensive. Yet the reactive glaze on the left needs it. Spodumene has a high enough Li2O concentration to be a possible source here. It also has a complex chemistry, but the other oxides it contains are those common to glazes anyway. Using my account at insight-live.com, I did the calculations and got a pretty good match in the formulas (lower section in the green boxes). Then I made 10-gram balls and did a GLFL test at 2200F (notice the long crystals in the glass pools below the runways). Not surprisingly, this recipe is very runny, that's why the tiny yellow crystals grow during cooling. The new version fires very similar, perhaps better. Our calculated cost in 2022 was $17.84 vs. $10.40 per kg. But there is a practical cost: Poor slurry properties. The spodumene sources so much Al2O3 that 70% Alberta Slip had to be dropped to accommodate it! How does one use this type of glaze without ruining kiln shelves? Using a catcher glaze is one answer.

Example of a commercial spodumene 2022

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Our theoretical chemistry is fairly close to this (notice these numbers are not precise, they indicate a range or minimum).

Spodumene can bubble when mixed with water.

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This is what happens when some spodumenes are mixed with water. They generate foam and bubbles. This is disruptive in glazes and can be alleviated by washing and drying the powder before use. Or calcining at 500-600F.

A problem with spodumene fluxed glazes: bubbles, surface dimples

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This is a closeup of G3813B, a recipe with 11% spodumene. Although the glaze is very glossy, its surface is marred by tiny dimples, the remnant of broken and partially healed bubbles escapes. These bubbles were in the laydown and dried in place (the spodumene generates these in the slurry itself, making it frothy). This can be reduced by drop-and-hold firing techniques, but a better answer is to find a frit to source the Li2O.

Adding spodumene to this floating blue tones down the white patches

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GA6-C (left) and GA6-E (right) at cone 6 oxidation. The E version adds 4% spodumene onto the 4% rutile in the C (the base is 80% Alberta Slip and 20% frit 3134). The spodumene eliminate the overly whitish areas that can appear. This glaze requires the "Slow Cool (Reactive Glazes)" firing schedule. It looks the best on dark bodies.

Spodumene glaze with natural ironstone concretion speckle

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L3362A speckle test cone 10R (G2240 spodumene) using ground ironstone concretions (50% 70-100 mesh, 35% 50-70 mesh, 15% 40-50 mesh) at 0.5%, 0.3%, 0.1% (left to right).

Here is why Spodumene powder glistens in the light

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Why Spodumene powder glistens in the light

Spodumene ceramic grade, used in glazes, is a 200 mesh material. How could the particles be big enough to glisten in the light? This is a micrograph of some of the particles from the 0.6% plus 100 mesh material that I extracted in a particle size distribution test. And 8% is plus 200 mesh. And all that material is flakey like this, millions of tiny mirrors. This also explains why the material becomes airborne so easily and why it is really not good to breathe this stuff in.

Here is why Petalite and Spodumene will seldom substitute for Lithium Carbonate

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Lithium carbonate vs petalite vs spodumene

Of course, if a recipe only calls for 1-5% lithium carbonate either of these might be candidates to supply the Li2O. However, Petalite is eight times less and Spodumene five times less concentrated than lithium carbonate so to make either worthwhile the prices would need to be eight and five times cheaper. But if a recipe calls for more there is another problem: Petalite is extremely high in silica, which means supplying the needed Li2O from it is almost certainly going to oversupply SiO2. Spodumene will likely do the same. Both are also high in Al2O3 and likely to oversupply that (or at minimum supply the bulk preventing the presence of kaolin in the recipe).

Links

Materials Laguna Spodumene Substitute
Materials Fusion Frit F-493
This frit is very valuable for one simple reason: It is a higher-quality source of Li2O for glazes than raw lithium carbonate. It contains 11% Li2O.
Materials SC7.0 Spodumene
Materials Australian Spodumene
Materials Foote Spodumene
Materials Spodumene Concentrate
Materials Lithium Carbonate
A powerful melter very valuable in ceramic glazes. It is 40% Li2O and has an LOI of 60% (lost as CO2 on firing). This material in now incredibly expensive.
Materials Montebrasite Concentrate
Materials Petalite
Materials Amblygonite
Materials Lepidolite
Materials SC 1.1 Spodumene
Materials CGS 3.1 Spodumene
Materials SC 1.2 Spodumene
Materials Feldspar
In ceramics, feldspars are used in glazes and clay bodies. They vitrify stonewares and porcelains. They supply KNaO flux to glazes to help them melt.
Materials FSC 2.1 Spodumene
Materials UGS Spodumene
Materials Triphylite
Oxides Li2O - Lithium Oxide, Lithia
URLs https://www.thecanadianencyclopedia.ca/en/article/spodumene
Spodumene at The Canadian Encyclopedia
URLs https://corelithium.com.au/
Core Lithium spodumene project in Australia
URLs https://en.wikipedia.org/wiki/Lithium_mining_in_Australia
Lithium Mining in Australia at Wikipedia
URLs http://www.talisonlithium.com/
Talison Lithium website
URLs http://en.wikipedia.org/wiki/Spodumene
Spodumene at Wikipedia
URLs https://www.talisonlithium.com/lithium
Technical Information about Spodumene from Talison website
Glossary Pyroceramics
Typecodes Feldspar
The most common source of fluxes for high and medium temperature glazes and bodies.
Typecodes Generic Material
Generic materials are those with no brand name. Normally they are theoretical, the chemistry portrays what a specimen would be if it had no contamination. Generic materials are helpful in educational situations where students need to study material theory (later they graduate to dealing with real world materials). They are also helpful where the chemistry of an actual material is not known. Often the accuracy of calculations is sufficient using generic materials.
Hazards Lithium Toxicology
Hazards Feldspar
Feldspars are abundant and varied in nature. They contain small amounts of quartz (while nepheline syenite does not).
Temperatures Spodumene melts (1418-1428)
Temperatures Spodumene converts to beta phase (1082-)

Data

Frit Softening Point 1421C M
Density (Specific Gravity) 2.60
By Tony Hansen
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